Electrical connector having constrained spring means



E. L.v HADDEN Jan. 28, 1969 ELECTRICAL CONNECTOR HAVING CONSTRAINED SPRING MEANS Filed May 26, 1967 United States Patent 6 Claims ABSTRACT OF THE DISCLOSURE An electrical connector having oppositely disposed semi-elliptical spring members extending between end sections defining a contact-engaging section, the end sections being held in position to prevent elongation of the spring members when a contact member is inserted within the contact-engaging section so that a large area of contact is effected between the spring members and contact member.

This invention relates to electrical connectors and more particularly to electrical connectors having constrained spring means.

Electrical connectors are known which have contactengaging sections provided with spring members which are not constrained against elongation correlative to leaftype deflection occurring during engagement with the mating contact element.

Such resilient contacts of low-rate spring-nature usually undergo a linear force/deflection arch-flattening phase which results in an increase in the arch radius. During this phase, the contacting area between the cooperating connector elements proceeds from a theoretical line (or point) contact at the tangent to a theoretical wider line contacting area.

The broad objective of this invention is to achieve a high rate compliant spring contact system wherein the spring rate increases exponentially and there is a concomitant exponential increase in the contacting area so as to result in a force/area (pressure) relationship that tends to remain substantially constant.

Ideally, the force/ area exponentials would be identical. The relationship of the exponents is dependent upon the progressive geometric relationship of any particular spring. The force/area exponents will be difierent and, chart-wise, there will be a cross-over point. It is expected in practice that a usable zone enveloping this cross-over point will provide an optimum electrical contact system with high current carrying capability, long life over repeated matings and unmatings and minimum contact electrical resistance. It is not intended that the present contact system be limited to this optimum zone.

An object of the invention is to provide an electrical connector having spring means in the connection area constrained against elongation.

Another object of the invention is the provision of an electrical connector having spring means in the connection area providing a large area of contact.

A further object is to provide an electrical connector that provides uniform contact pressure along the connection area.

An additional object is the provision of an electrical connector having one or more elliptical spring members in the connection area constrained against elongation during electrical engagement with a contact element.

A still further object is to provide an electrical connector having a compensatory action during the initial engagement between the contact-engaging section of the electrical connector and a contact element resulting in a constant pressure range and therefore a relatively great wear life of repeated cycling.

3,425,030 Patented Jan. 28, 1969 Still an additional object is to provide an electrical connector having a ferrule member oifset with respect to the contact section to obtain greater density when applied onto a contact element.

Other objects and attainments of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings in which there are shown and described illustrative embodiments of the invention; it is to be understood, however, that these embodiments are not intended to be exhaustive nor limiting of the invention but are given for purposes of illustration in order that others skilled in the art may fully understand the invention and the principles thereof and the manner of applying it in practical use so that they may modify it in various forms, each as may be best suited to the conditions of a particular use.

The foregoing and other objects are achieved by a preferred embodiment of an electrical connector including a support section having a connection section for engagement with conductive means and a contact-engaging area, the contact-engaging area having end sections and connecting-section means connecting the end sections together, the connecting-section means including contact spring means disposed between the end sections and di rected towards an insertion axis of the contact-engaging area, and means provided by the connecting-section means and the support section maintaining the end sections in position thereby preventing the contact spring means from elongating during engagement with a contact element upon movement thereof within the contact-engaging area.

In the drawings:

FIGURE 1 is a perspective view of electrical connectors in position on a contact element;

FIGURE 2 is an exploded perspective view of an electrical conductor, electrical connector and contact element;

FIGURE 3 is a view taken along line 3-3 of FIG- URE 4;

FIGURE 4 is a view taken along line 44 of FIG- URE 3;

FIGURES 5a and 5b are diagrammatic views respectively illustrating the spring means of the electrical connector prior to engagement with a contact element and after engagement of the spring means with the contact elements; and

FIGURE 6 is a view taken along line 66 of FIGURE 2 illustrating an embodiment of the electrical connector.

Turning now to the drawings and more particularly FIGURES 1 through 4, there is illustrated an electrical connector EC which comprises a support section 1 from which a ferrule member 2 and a contact section 3 extends. The connector is susceptible to mass production by automatic machinery and is conveniently formed by shaping a sheet metal blank or strip of suitable electrically conductive metal such as, brass, bronze, or the like in successive forming steps. The metal is sufliciently hard and resilient to impart to the contact section a spring-like character, yet it is sufficiently malleable to permit coldforging or crimping of the ferrule member onto a conductor to provide an excellent electrical and mechanical connection.

Ferrule member 2 includes a conductor-engaging section and an insulation-engaging section crimpable by conventional crimping dies (not shown) onto electrical conductor 4. Support section 1 includes an extension 5 disposed at right angles therewith to provide rigidity to the support section. Support section 1 also includes an elongated opening 6.

Contact section 3 includes end sections 7 and 8 and their connecting sections 1a, 9, 10 and 11 which extend between end sections 7 and 8 and connect them together to form a receptacle. Connecting section 10 includes lugs 12 which extend through an elongated opening 6 and are bent into engagement with support section 1 by a coining operation to complete the formation of the receptacle as well as to maintain end sections 7 and 8 in position thereby precluding movement thereof because lugs 12 are disposed adjacent the ends of opening 6. Lugs 12 also lock the contact section in the formed configuration.

Connecting sections 9 and 11, as illustrated in FIGURE 4, are disposed opposite each other and provide contact springs of semi-elliptic configuration for engagement with contact element 13. Contact section 3 may be formed with one or more contact springs as desired. As illustrated, contact section 3 has a generally rectangular configuration to conform to the similar configuration of mating contact element 13; however, contact section 3 can take any geometrical configuration to achieve the electrical connection with a contact element for insertion therein. End section 8 constitutes the entrance to contact section 3 and includes a beveled surface 14 to facilitate the insertion of contact element 13 therein.

In operation, as illustrated in FIGURES 5a and 5b, which illustrate only the operation of spring contact 9, contact element 13 is inserted within contact section 3 causing spring contact 9 to engage a large area of contact element 13 because end sections 7 and 8 are constrained from any movement. The same action occurs with respect to spring contact 11.

Since the semi-elliptic springs 9 and 11 are restrained against any axial movement by means of tie-bar effect of elements 1a and 10, this provides large area contact between springs and the mateable contact member. Contact section 3 takes advantage of the conformity of the spring members to the surface of the contact element to engage therewith thereby increasing contact area therebetween with a concomitant increase in spring force. The relationship of the area to first of contact section when being electrically engaged with a contact element is governed by different factors which are not compensatory but have a cooperating relationship tending to retard an increase of pressure as the force increases. At the early stage of this area to force relationship, a small range of action where the area to force relationship is compensatory occurs whereby resulting in a constant pressure range and therefore a relatively great wear life of repeated cycling. Also, a geometrical relationship may exist wherein the elliptical spring contacts operate like a toggle linkage and can generate an excessive compressive force within the spring contact or contacts causing failure as a column and to buckle during engagement with a contact element. As the compressive strength approaches the compression limit of the bending stress (arch prestress), the contact force at the center of the elliptical spring approaches zero. Moreover, as the compressive stress overwhelms the columnar strength of the elliptical spring, the center of the elliptical spring is likely to move rapidly away from contact with the contact element until the stresses contained in the ellipitical spring provide an equilibrious couple.

FIGURE '6 illustrates an alternative embodiment of the invention wherein lugs 12 have their ends subjected to a swagin-g operation to rivet the lugs in corresponding openings in support section 1' of electrical connector EC; otherwise the electrical connector of FIGURE 6 is the same as the electrical connector of FIGURES 1 through 4.

As illustrated in FIGURE 1, ferrule member 2 is offset with respect to contact section 3 in such a manner so that the ferrule member of the leading electrical connector when disposed on contact element 13 is disposed adjacent the contact section of the next succeeding electrical connector on the same element 13 to provide greater density and this is accomplished by placing one electrical connector on contact element 13 and rotating the other electrical connector 180 before insertion onto contact element 13. Insulation means may be applied to ferrule members 2 of the electrical connectors to provide insulation means therefor.

Thus, as can be discerned, there has been disclosed a unique and novel electrical connector having ellipitical spring contact members that are restrained against axial movement.

It will, therefore, be appreciated that the aforementioned and other desirable objects have been achieved; however, it should be emphasized that the particular embodiments of the invention, which are shown and described herein, are intended as merely illustrative and not as restrictive of the invention.

The invention is claimed in accordance with the following:

1. An electrical connector including a support section having a connection section for engagement with conductive means and a contact-engaging area, the contactengaging area having end sections and connecting-section means connecting the end sections together, the connecting-section means including contact spring means disposed between the end sections and directed towards an insertion axis of the contact-engaging area, first means provided by the connection-section means, second means provided by the support section, said first and second means coact to maintain said end sections in position thereby preventing the contact spring means from elongating during engagement with a contact element upon relative movement therebetween.

2. An electrical connector according to claim 1 wherein said second means includes opening means in said support section and said first means includes lug means on one of said connecting-section means, said lug means extending through said opening means and into securing engagement with said support section.

3. An electrical connector for electrical engagement with a mateable contact element comprising a support section, a conductor-engaging section extending outwardly from said support section for electrical engagement with electrical conductor means, said support section having a contact-engaging area extending outwardly therefrom, said contact-engaging area including end sections and a connecting section extending between said end sections, said connecting section being disposed adjacent said support section, spring means extending between said end sections and being directed inwardly toward an insertion axis of said contact-engaging area, and securing means provided by both said support section and said connecting section, said securing means coact to maintain said end sections in substantially stationary positions to prevent said spring means from elongating during engagement with said contact element upon relative movement therebetween.

4. An electrical connector according to claim 3 wherein said conductor-engaging section is offset in a sidewise manner with respect to said contact-engaging area.

5. An electrical connector according to claim 3 wherein said contact-engaging area has a generally rectangular configuration in cross section.

6. An electrical connector according to claim 3 wherein said spring means constitute opposing spring members of generally arcuate configuration.

References Cited UNITED STATES PATENTS 3,188,606 6/1965 De Lyon et a1 339256 3,262,087 7/1966 Mancini 339256 3,317,887 5/1967 Henschen et a1 339--256 3,363,224 1/1968 Gluntz 339-258 3,369,212 2/1968 Coldren et al. 339-258 X MARVIN A. CHAMPION, Primary Examiner.

PERRY TEITELBAUM, Assistant Examiner.

US. Cl. X.R. 339276 

